1. Field of the Invention
The present invention relates to an imaging device, a signal processing method, and a computer program. More specifically, the present invention relates to an imaging device having a live view function for displaying images on a monitor such as a liquid crystal display (LCD), such as a single-lens reflex (SLR) camera, a signal processing method, and a computer program.
2. Description of the Related Art
Observation through optical viewfinders (OVFs) has been in the mainstream of observation of subjects using cameras. Recently, cameras having a “live view display” function for displaying image sensor (imaging element) outputs on displays such as LCDs disposed on the rear surface or the like of the cameras have been increasingly available. As compared to OVFs, viewfinders that use displays such as LCDs are referred to as electronic viewfinders (EVFs). A camera including an OVF and an EVF is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2006-267381.
In cameras having the live view display function, in which displays are used as viewfinders, it is necessary to process output signals of image sensors (imaging elements) to display live views. It is also necessary to process output signals of the image sensors (imaging elements) to perform photographing and recording processes. Various types of signal processing on image sensor outputs, such as white balance adjustment, gain control, gamma (γ) correction, and color correction, are executed using an image signal processing circuit formed of an integrated circuit (IC) chip or the like.
In a camera involving no display processing in which imaging element outputs are used only for recording processes, as shown in FIG. 1, the output of an image sensor 1 is output to a signal processing chip 2 and the output of the signal processing chip 2 is recorded. The signal processing chip 2 is used only for recording processes. Data transfer between the image sensor 1 and the signal processing chip 2 is performed using, for example, a Sub-Low Voltage Differential Signal (subLVDS) transmission system that allows high-speed data transfer.
Cameras having the live view display function, on the other hand, are provided with an image sensor that outputs data used for recording processes and a sub-image sensor that outputs data used to display live views, and output signals of both image sensors are processed. For example, a camera having more than one, a plurality of image sensors (N image sensors) may be configured to include, as shown in FIG. 2, a plurality of sets (N sets) of image sensors 3-1, to 3-N and signal processing chips 4-1 to and 4-N connected to each other in a one-to-one correspondence. However, signal processing chips are relatively expensive, and the structure described above may lead to an increase in cost.
FIG. 3 shows a structure for reducing the number of signal processing chips which are expensive. As shown in FIG. 3, a single signal processing chip 6 is provided with interfaces serving as input units that receive signals from a plurality of image sensors 5-1 to 5-N. The signals received from the image sensors 5-1 to 5-N are switched and processed in the signal processing chip 6. However, this structure has a problem in that, due to the necessity of providing the signal processing chip 6 with additional functions, namely, an interface function for implementing a plurality of inputs and a switching function for switching processing signals, it is difficult to use an existing chip, which may result in a demand for the development of a new chip.